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serial: imx: Introduce timeout when waiting on transmitter empty

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[ Upstream commit e533e4c62e ]

By waiting at most 1 second for USR2_TXDC to be set, we avoid a potential
deadlock.

In case of the timeout, there is not much we can do, so we simply ignore
the transmitter state and optimistically try to continue.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/919647898c337a46604edcabaf13d42d80c0915d.1712837613.git.esben@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Esben Haabendal 2024-04-11 14:19:23 +02:00 committed by Greg Kroah-Hartman
parent 38d647d509
commit 53b2c95547
1 changed files with 4 additions and 3 deletions
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7
drivers/tty/serial/imx.c
View file

@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/dma-mapping.h>
#include <asm/irq.h>
@ -2010,7 +2011,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
struct imx_port *sport = imx_uart_ports[co->index];
struct imx_port_ucrs old_ucr;
unsigned long flags;
unsigned int ucr1;
unsigned int ucr1, usr2;
int locked = 1;
if (sport->port.sysrq)
@ -2041,8 +2042,8 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
* Finally, wait for transmitter to become empty
* and restore UCR1/2/3
*/
while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,
0, USEC_PER_SEC, false, sport, USR2);
imx_uart_ucrs_restore(sport, &old_ucr);
if (locked)